if you put the sub on top and port firing back, that'll allow the box to be a lil shorter which helps with port sizing. i came up with
14" high
41" wide (to fit between the wheel wells)
23.5" deep
with a port of 5" high, 9" wide, and 15" deep.
the port is a lil on the small side as far as square inches go, but if you have a 9515 i'm sure you have somethin nice to power it, so a smaller port *shouldnt* hinder it any.